Lubricant compositions

ABSTRACT

LUBRICANT COMPOSITIONS ARE PROVIDED CONTAINING BIOCIDAL EFFECTIVE AMOUNTS OF A SUBSTITUTED NITROPYRIDINE AND AN ACID.

United States Patent 3,826,746 LUBRICANT COMPOSITIONS John W. Schick, Cherry Hill, and Robert H. Davis, Pitman, N.J., and Charles .A. Simpson, Aston, Pa., assignors to Mobil Oil Corporation No Drawing. Filed July '18, 1972, Ser. No. 273,002

' Int. Cl. C10m I/32, 3/26 US. Cl." 2525-515 R 6 Claims ABSTRACT OF THE DISCLOSURE Lubricant compositions are provided containing biocidal effective amounts of a substituted nitropyridine and an acid.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to lubricant compositions and, in one of its aspects, relates more-particularly to petroleum lubricant compositions containing biocidal agents as microbial inhibitors. Still more particularly, in this aspect, the invention relates to novel biocidal compositions whichare effective in inhibiting microbial growth, particularly in such media as petroleum lubricant compositions.

Description of the Prior Art The use of substituted pyridine N-oxides as biocidal agents is known'to those skilled in the art. However, it

has: been found that only limited bacteria growth inhibi- In accordance with the present invention new and improved lubricant compositions are provided, having improved bacterial growth inhibition, containing a biocidal effective amount of an agent comprising a substituted nitropyridine and an acid.

Illustrative of the substituted nitropyridines that can be employed in the novel biocidal agents are 4-nitropyridine N-oxide, 2-methyl-4-nitropyridine N-oxide, 5- ethyl-2-methyl-4-nitropyridine N-oxide, or compounds illustrated as follows:

in which R is oxygen; R R represent hydrogen, alkyl, halogens, amino (NH nitro (N0 or combinations thereof. However, inall instances at least one nitro group must be present, preferably in the R position.

The acid employed in the biocidal agent, in combination with the substituteed nitropyridine, may comprise any organic or inorganic acid. Preferably, the organic acid may comprise organic acids having from about 1 to about 40 carbon atoms, and particularly preferred are acids having from about 6 to about 18 carbon atoms. Illustrative of these acids are caprylic acid, pelargonic acid, undecenoic acid, oleic acid, stearic acid, ricinoleic acid, dimer and trimer acids and the like. Illustrative of the inorganic acids are hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid and the like.

In the novel biocidal agents of the present invention, the substituted pyridine is efiectively employed in an amount from about .01 to about 40%, and preferably from about 0.1 to about 10%, by weight. The acid is effectively employed in an amount from about 0.1 to about 60%, by weight, and preferably in an amount from about 0.5 to about 30%, by Weight.

The biocidal agent is effectively employed, for in hibiting bacterial growth, in any lubricant media and may include cutting oils, penetrating oils, grinding lubricants, core oils, hydraulic fluids or greases and other media which are ordinarily subject to breakdown by bacteria which tend to metabolize the hydrocarbons and result in the formation of deleterious metabolities.

Representative substituted nitropyridines of the present invention may be prepared in several ways. Thus 4-nitropyridine N-oxide may be prepared in the following manner:

79 grams, 1.0 mole, of pyridine and 30 grams, 5.0 mole of acetic acid are mixed and 30% of hydrogen peroxide grams, 0.75 mole) are added. This mixture is heated at 80 C. for a period of 2 hours and another portion of 30% hydrogen peroxide (50 grams, 0.44 mole) are added. The resulting mixture is heated for an additional 2 hours and, again, 30% hydrogen peroxide (35 grams, 0.31 mole) are added. The resulting mixture is then heated for an additional 2 hours. The total heating time at 80 C. is 6 hours and the total amount of 30% hydrogen peroxide is 170 grams, 1.5 moles.

The final mixture is then cooled to room temperature and the excess peroxide is decomposed by bubbling in sulfur dioxide. After the decomposition of the peroxide is complete, the acetic acid is removed by distillation under reduced pressure. The pyridine N-oxide residue is taken up in sulfuric acid (177 ml.) with cooling. A mixture of nitric acid (217 ml.) and sulfuric acid (90 ml.) is slowly added. One-half of the acid mixture is added and the reaction mixture is then heated to 70 C. A slight exothermic reaction occurs and the temperature is controlled at 90 C. The remainder of the acid mixture is then added. The resulting mixture is then heated at 90 C. for a period of 3 hours. The excess nitric acid is removed by distillation under reduced pressure. The residue is poured over 300 grams of ice and neutralized to a pH of 6 with 610 ml. of 50% sodium hydroxide. The solid and liquid are extracted with 3X 500 ml. of chloroform. The chloroform extract is concentrated to a thick slurry and the solid is filtered. A yellow solid is obtained weighing 93.9 grams, 67% yield and a melting point of -62 C.

To obtain 2-methyl-4-nitropyridine N-oxide, having a melting point of 15456C., the same procedure, as described above, employing alpha-picoline in place of pyridine, is carried out. Similarly, to obtain 5-ethyl-2- methyl-4-nitropyridine N-oxide, having a melting point of 79-80 C., the same procedure is employed, but using 5-ethyl-2-methylpyridine in place of pyridine.

Other known methods for producing these and other substituted nitropyridines of the present invention may also be efiectively employed.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following test procedure was employed for determining the biocidal activity of the novel biocidal agents investigated in accordance with the present invention:

In this procedure A" x /2" x .027" thick filter paper was saturated with the biocidal test solution (approximately /2 ml.). This square was placed in the center of a nutrient agar plate previously inoculated with bacteria 3 (predominantly pseudomonas). In this test an effective biocidal agent should inhibit growth adjacent to the filter paper. The distance from the edge of the paper to the point where bacterial growth begins, is indicative of activity.

As is shown in the data of the following table, if 4-nitropyridine N-oxide, as a representative substituted nitropyridine, is omitted (Example 1), from a typical cutting fluid formulation containing 3%, by weight, of caprylic acid, little inhibition of bacterial growth adjacent to the filter paper, is realized. The data of Example 2 indicates that a 1%, by weight, addition of 4-nitropyridine N-oxide to this same formulation, "but without the presence of the caprylic acid, results in only a slight growth inhibition, approximately A" from the filter paper. However, as is shown in Example 3, the activity of the substituted nitropyridine is greatly enhanced if caprylic acid is present wherein bacterial growth is prevented in an area of about from the test paper.

TABLE Antimicrobial properties-Aqueons coolant containing 4-nitropyridine N-oxide Percent by weight Exam- Exam- Exam- Composition pie 1 pie 2 ple 3 4-nitropyridine N- oxide 0. O 1. O0 1. 00 Caprylic acid 3. 00 0. 00 3. 00 Boric acid 3. 00 3. O0 3. 00 Triethannlaminn 26. 0O 26. 0O 26. O0 Monoethanolamine- 4. 0O 4. 0O 4. 00 Sodium nitrite 8.00 3. 00 3.00 Benzotriazole 0. 25 0. 25 0. 25 Copolymer of ethylene oxide-propylene oxide-- 5. 00 5. 00 5. 00 Water 75 57. 75 54. 75

Biocide activity test: Bacterial growth inhibition, inches from test square Me Aside from their outstanding biocidal eflicacy in inhibiting bacterial growth in lubricant compositions, the biocidal agents of the present invention may also be employed for similar effect in such media as cosmetics, wax emulsions, cleaning solutions for dairy equipment and as a biocidal agent for treatment of skin disorders or other medical purposes.

Although the present invention has been described with certain specific and preferred embodiments, for purposes of illustration, it will be understood that various modifications and adaptations thereof, which will be obvious to those skilled in the art, may be made without departing from the spirit of the invention.

We claim:

1. A lubricant composition containing a biocidal elfective amount of an agent comprising (a) from about 0.01

to about 40%, by weight, of a substituted nitropyridin having the formula: a. 1%!

Rs R2 in which R is oxygen; R to R represent hydrogen, alkyl, halogens, NH N0 or combinations thereof and in which at least one of R to R is N0 and (b) from about 0.1 to about by weight of an acid selected from the group consisting of organic acids having from about 1 to about 40 carbon atoms in which only hydrogen and carboxyl groups are bonded to carbon, and inorganic acids.

2. The lubricant composition of claim 1 wherein said agent comprises from about 0.1 to about 10%, by weight, of the substituted nitropyridine and from about 0.5 to about 30%, by weight, of the acid.

3. The lubricant composition of claim 1 wherein said substituted nitropyridine is 4-nitropyridine N-oxide.

4. The lubricant composition of claim 1 wherein said substituted nitropyridine is 2 methyl-4-nitropyridine N-oxide.

5. The lubricant composition of claim 1 wherein said nitropyridine is 5-ethyl-2-methyl-4-nitropyridine N-oxide.

6. The lubricant composition of claim 1 wherein said acid is an organic acid having from about 6 to about 18 carbon atoms.

References Cited UNITED STATES PATENTS 2,228,325 1/1941 Olin et al 252515 AX 2,372,588 3/1945 Larsen et al. 25251.5 AX 3,166,507 1/1965 Bailey et a1. 25251.5AX 3,288,713 11/1966 Eickemeyer et al.

25251.5 A X 3,303,131 2/1967 Low et al. 252475 3,058,959 10/1962 Bailey et al. 25251.5AX 2,353,169 7/1944 Lincoln et a1. 25249X OTHER REFERENCES Chemical Abstracts, 57, pp. 9958h, 19, 169 S (subject index); 1962.

DANIEL E. WYMAN, Primary Examiner P. F. SHAVER, Assistant Examiner U.S. Cl. X.R. 

